1. Field of the Invention
The invention relates to an encapsulated installation for electrical power having a plurality of sensors disposed in the interior.
German Utility Model 94 20 199 discloses a metal-encapsulated high-voltage switching installation in which a surface acoustic wave element (SAW) is disposed in one of its gas areas. The SAW is used to verify gas constituents, which are produced by the effect of arcing on extinguishing gas that is contained in the encapsulation, or to detect pressure waves. In that case, an antenna, which is used for wireless information transmission to an evaluation device, is disposed on the outside of the encapsulation. German Patent DE 195 14 342 C1, which was issued subsequent to the priority date of the instant application and corresponds to U.S. Pat. Application Ser. No. 08/953,965 filed Oct. 20, 1997, discloses the use of SAW sensors in a high-voltage cable.
The use of SAW sensors in high-voltage technology is known, in principle, from an article entitled "Akustische Oberflachenwellen-Technologie fur Innovationen" [Surface Acoustic Wave Technology For Innovations] in Siemens-Zeitschrift Spezial [Siemens Journal, Special] FuE, Spring 1994. That article also provides for the SAW sensor to be mounted in a container, and for its antenna to be mounted externally.
2. Summary of the Invention
It is accordingly an object of the invention to provide an encapsulated installation, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which provides a simple solution for the configuration of transmitting and receiving elements for information transmission on an encapsulated installation for electrical power, in which the intention is to permit reliable monitoring.
With the foregoing and other objects in view there is provided, in accordance with the invention, an encapsulated installation for electrical power, comprising an encapsulation having an interior and defining different gas areas; a plurality of sensors to be interrogated selectively, the sensors having respective transmitting/receiving elements, at least some of the sensors disposed in the interior, and at least some of the sensors disposed in the different gas areas; and a monitoring device having an antenna element for information interchange with the sensors, the antenna element disposed at the encapsulation and directed towards the interior.
This solution makes it possible to monitor a large number of functions through the use of remote interrogation using simple measures, without any wiring or mechanical outlay being incurred inside the encapsulation. Only the desired sensors need be fitted. This solution is also suitable for existing installations and can easily be extended. It is possible to accommodate the sensors in the encapsulation of the installation, even in unfavorable space conditions.
In accordance with again another feature of the invention, the sensors are preferably constructed as surface acoustic wave sensors (SAW). These sensors have a small physical size and high reliability. This permits accommodation in the interior of the encapsulation in a manner which is favorable during service, and a high level of safety during operation is provided. In one specific embodiment, the size of the sensor may be roughly that of a check card, with the majority of its form advantageously being used as an antenna element.
In accordance with another feature of the invention, at least some of the sensors are constructed to detect different measurement variables, as a result of which it is possible to detect a multiplicity of different information items and/or measurements. In this case, the sensors can be disposed in different subareas, in particular gas areas, in the installation. This applies, of course, only to the extent that information transmission is possible between two subareas through their compartmentalization.
In accordance with a further feature of the invention, the sensors may be constructed as active or preferably as passive components. In this way, account can be taken of the respective conditions at the respective installation location. A passive structure has the advantage that no electronics at all need be used. This is favorable for use at high voltages.
In accordance with an added feature of the invention, the sensors are disposed in the encapsulation at the potential of the encapsulation or at the potential of a conductor. This does not result in any limitation to specific detection values, potential conditions or installation locations. The installation location may even be movable (for example on a switching rod). No additional potential isolation devices are necessary.
In accordance with an additional feature of the invention, the monitoring device has at least one additional interface for information interchange with other sensors, SAWs, measurement sensors or detection devices. Overall incorporation of other information sources, even outside the encapsulation, is thus possible, which results in a multisensor concept.
In accordance with yet another feature of the invention, the other interface or interfaces can be constructed as a cable-based interface or interfaces, in particular an electrical, acoustic or optical interface or interfaces, or as a wireless interface, as a result of which it is possible to couple a wide range of information sources thereto.
In accordance with yet a further feature of the invention, there is provided an interface for coupling a monitoring device, which is at an equivalent or higher level, thereto. The interface can then preferably be constructed as a bus interface, as a result of which a high data transmission rate is possible.
In accordance with yet an added feature of the invention, coding is provided for selective interrogation. In this way, it is possible to distinguish between the respective information items and the assignment of the respective sources or sensors. The coding can be implemented by hardware or by a procedural measure, for example software.
In accordance with yet an additional feature of the invention, different frequencies may be assigned for information transmission to the respective sensors, for coding. Each sensor thus has its own information path or channel.
In accordance with again another feature of the invention, the coding can alternatively or additionally be carried out in conjunction with a frequency or time division multiplex method. This enables favorable, multiple use of existing frequency channels.
In accordance with again a further feature of the invention, the coding can be carried out by polarization, for example of the electromagnetic wave being used, possibly using a directional antenna, or correlation. This type of coding is favorable for use in metal encapsulation. Correlation methods are known in principle from radar technology, wherein a signal pattern is transmitted back with a response signal of the sensor and the signal pattern is identified by correlation.
In accordance with again an added feature of the invention, the coding can also be carried out through the use of an identification in the transmission or response signal during the information interchange. This results in a selective identification capability in the transmitting and receiving device in each case.
In accordance with again an additional feature of the invention, the encapsulation is metallic. This results in a preferred use of the installation for high or medium voltage. The information items which occur in a wide ranging manner there can thus be processed safely and easily. This also provides internal and external screening.
In accordance with still another feature of the invention, there is provided at least one switching device or a conductor inside the encapsulation. The installation is thus then constructed as a switching installation or tubular conductor.
In accordance with a concomitant feature of the invention, the antenna elements can optionally be constructed for the transmission of optical, acoustic or electromagnetic waves. This solution is optimized for high transmission reliability and high interference immunity with the maximum possible transmission rate, depending on the application. The present solution is particularly simple and can be integrated into new and existing installations without any problems. The antenna elements are fitted without any complex measures.
Comprehensive monitoring of a switching installation, of a tubular conductor or of an encapsulated component is possible through the use of the invention. It is possible to interrogate a multiplicity of sensors, in particular SAWs, remotely and selectively through one antenna element. In this case, the monitoring can be carried out accurately with respect to the gas area, with a considerable cost and complexity saving being provided, particularly in the case of large gas-insulated switching installations, in comparison with cable-based monitoring.
The term "encapsulated installation" predominantly and in general means installation parts for electrical power distribution, in particular for high or medium voltage, which have an encapsulation, a housing or a tank in which at least one electrical component is accommodated. Examples of this are: an encapsulated switch disconnector or circuit breaker, an encapsulated switching mechanism, an SF.sub.6 -insulated transformer or an SF.sub.6 tubular conductor.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an encapsulated installation, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.